Researchers from Stanford University have made a groundbreaking discovery in the treatment of depression: they have found that certain brain signals flow the wrong way in people with treatment-resistant depression, and that magnets can correct this and help them feel better. For the first time in psychiatry, the misdirection of certain signals between two brain regions predicts the change in clinical symptoms. While the majority of people with depression can find some relief through medication, approximately 84 million people worldwide have treatment-resistant depression, in which they do not feel better even after trying multiple antidepressants.
About 50% of people with treatment-resistant depression respond to transcranial magnetic stimulation (TMS), according to Adam P. Stern, MD, an assistant professor of psychiatry at Harvard Medical School, who was not involved with the study. TMS uses magnetic fields to stimulate nerve cells in the brain, usually five days a week for several weeks or months. While this therapy has been well received, how it works has remained something of a mystery, making it hard to determine which patients are likely to benefit from it.
To determine how TMS affects the brain, researchers from Stanford University recruited 33 people with treatment-resistant depression for a study published in PNAS. Twenty-three were given an accelerated version of TMS called “Stanford neuromodulation therapy”, consisting of ten daily sessions for five days, whilst the others received a sham treatment. All participants underwent functional magnetic resonance imaging (fMRI) of their brains before and after the trial so that researchers could map their brain activity.
During this process, researchers found a connection between the anterior insula, which regulates physical sensations, and the anterior cingulate cortex, which governs emotions. Signals in people without depression flowed from the anterior insula to the anterior cingulate cortex. However, 75% of people with depression in the study had some wrong-way signals, and the more severe the depression, the greater the proportion of wrong-way signals.
The researchers said it was almost as if people with depression had already decided how they were going to feel, and then everything they sensed was filtered through that feeling. However, within three days of finishing the TMS treatment, the misdirected signals were flowing in the right direction. Patients were reporting an improvement in their mood, and those with more severe depression experienced even greater improvement.
While not everyone with treatment-resistant depression displayed the misdirected signals, this discovery may prove to be a helpful indicator that a person has depression and is likely to respond to TMS. According to senior author Mark Raichle, “Behavioral conditions like depression have been difficult to capture with imaging because, unlike an obvious brain lesion, they deal with the subtlety of relationships between various parts of the brain. It’s incredibly promising that the technology now is approaching the complexity of the problems we’re trying to understand.”
In conclusion, this discovery could be a major step forward in the treatment of depression, particularly for those struggling with treatment-resistant depression. The fact that signals flow the wrong way in the brains of people with depression is a groundbreaking finding, as well as the discovery that magnets can correct this misdirection and improve their mood. Further research could lead to more effective treatments for depression.
